We propose to isolate and identify the toxins produced by algae of both marine and freshwater environments. These toxins are hazardous to humans directly or following ingestion of the toxins by animals commonly used as human food resources. As a result, these food resources are denied for human consumption or if unknowingly used, can cause severe discomfort, acute toxicity, or even death. Culture techniques have been developed at Brookhaven for growing microalgae on a large scale. Environmental conditions for maximal algal growth will be determined to assure sufficient material for continuous chemical investigation. The effects of environmental factors on toxin production will be investigated. In those frequent instances where several toxins are produced by an alga, the biosynthetic mechanisms influencing the relative amounts of the toxin will be examined. Knowledge derived from these studies will be useful for developing methods to decrease or eliminate toxin production or toxic algal growth. The algal toxins will be isolated and characterized as pure chemical compounds at Berkeley and will be subjected to structural investigations and synthesis.